DE112015005347T5 - Bearing component formed from a steel alloy - Google Patents

Abstract

The present invention provides a bearing component formed from a steel alloy having: 0.7 to 0.9 wt% carbon, 0.05 to 0.16 wt% silicon, 0.7 to 0.9 Wt% manganese, 1.4 to 2.0 wt% chromium, 0.7 to 1.0 wt% molybdenum, 0.03 to 0.15 wt% vanadium, 0 to 0.25 % By weight of nickel, 0 to 0.3% by weight of copper, 0 to 0.2% by weight of cobalt, 0 to 0.1% by weight of aluminum, 0 to 0.1% by weight of niobium, 0 to 0.2 wt% tantalum, 0 to 0.025 wt% phosphorus, 0 to 0.015 wt% sulfur, 0 to 0.075 wt% tin, 0 to 0.075 wt% antimony, 0 to 0 , 04% by weight of arsenic, 0 to 0.002% by weight of lead, up to 350 ppm of nitrogen, up to 20 ppm of oxygen, up to 50 ppm of calcium, up to 30 ppm of boron, up to 50 ppm of titanium, with the remainder iron along with any unavoidable impurities.

Description

Technical environment

The present invention relates generally to the field of metallurgy and to a bearing component made from a steel composition. The steel may be made by a continuous casting process.

background

Bearings are devices that allow limited relative movement between two parts. Rolling bearings include inner and outer races and a plurality of rolling elements (balls or rollers) interposed therebetween. For long term reliability and performance, it is important that the various elements that are typically made of bearing steel have resistance to rolling contact fatigue, wear and creep. Another important property of the bearing steel is its hardenability, that is, the depth to which the alloy is cured after being subjected to a heat treatment process.

An example of a type of bearing steel is material number (material) 1.3536 (DIN 100 CrMo7-3). This usually includes 1.0 wt% C, 0.30 wt% Si, 0.70 wt% Mn, 1.80 wt% Cr, 0.30 wt% Mo, and as Rest Fe and any unavoidable impurities.

Continuous continuous casting is an increasingly widely used process in the production of metal articles. The process involves solidification of molten metal into a semi-finished strand blank or ingot or slab for subsequent surface processing, heat treatment or hot working in finishing rolling mills. Continuous continuous casting provides improved yield, productivity and cost inefficiency.

Macrosegregation occurs during continuous casting due to the difference in the solubility of the dissolved elements in the liquid and solid phases. The result is a non-uniformity in the chemical composition of the steel which adversely affects the mechanical properties and day-to-day performance of the continuous casting steel articles. Macrosegregation refers to the variations in composition that occur in alloy castings and ingots, ranging from a few millimeters to centimeters.

Summary

It is an object of the present invention to provide a bearing component made of a steel composition which offers good mechanical properties and which can be produced by a process involving continuous continuous casting.

The above object is achieved by means of a bearing component made from a steel composition comprising:

0.7 to 0.9% by weight of carbon,
0.05 to 0.16% by weight of silicon,
0.7 to 0.9 wt.% Manganese,
1.4 to 2.0% by weight of chromium,
From 0.7 to 1.0% by weight of molybdenum,
0.03 to 0.15% by weight of vanadium,

0 to 0.25 wt% nickel,
0 to 0.3% by weight of copper,
0 to 0.2% by weight of cobalt,
0 to 0.1% by weight of aluminum,
0 to 0.1% by weight of niobium,
0 to 0.2 wt% tantalum,

0 to 0.025 wt.% Phosphorus,
0 to 0.015% by weight of sulfur,
0 to 0.075 wt% tin,
0 to 0.075 wt.% Antimony,
0 to 0.04 wt.% Arsenic,
0 to 0.002 wt.% Lead,

up to 350 ppm nitrogen,
up to 20 ppm oxygen,
up to 50 ppm calcium,
up to 30 ppm boron,
up to 50 ppm titanium,
as the remainder iron along with any unavoidable impurities.

The present invention will now be further described. In the following passages, different aspects of the invention are defined in more detail. Any aspect so defined can be combined with any other aspect or aspect unless clearly stated otherwise. In particular, all the properties which are designated as preferred or advantageous can be combined with another property or properties which are characterized as being preferred or advantageous.

In the present invention, the steel alloy composition used for the bearing component comprises 0.7 to 0.9 wt% of carbon, preferably 0.7 to 0.08 wt% of carbon, more preferably 0.72 to 0.78 Wt% carbon, more preferably 0.73 to 0.77 wt%. In combination with the other alloying elements, this results in a desirable microstructure and desirable properties. It has also been found that the reduced carbon content also results in lower levels of macrosegregation in continuously cast articles, such as billets or billets, without a negative effect on the hardness of the cured bearing components. Furthermore, the reduced carbon content means that the steel is easier to butt than conventional steels with a higher carbon content.

The steel alloy composition comprises 0.05 to 0.16 wt% silicon, preferably 0.06 to 0.16 wt% silicon, more preferably 0.08 to 0.14 wt% silicon, still more preferably 0, 09 to 0.12 wt .-% silicon, more preferably 0.1 to 0.12 wt .-% silicon. In combination with the other alloying elements this results in the desired microstructure with a minimum content of retained austenite. Silicon helps suppress precipitation of cementite and carbide formation. Silicon can also resist softening during tempering. However, too high a silicon content can result in undesirable surface oxides and poor surface finish. For this reason, the maximum silicon content is preferably 0.16 wt%. Steels with a higher silicon content tend to retain more austenite in their hardened structures due to the carbide-dominating characteristics of the element. It follows that the steel concentration of silicon can be reduced to reduce the retained austenite content. In addition, it has been found that silicon content within the above range also results in lower levels of macrosegregation in continuous, continuously cast billets and ingots from which the articles are made.

The steel composition comprises from 0.7 to 1.0% by weight of molybdenum, preferably from 0.7 to 0.9% by weight of molybdenum, more preferably from 0.7 to 0.85% by weight of molybdenum, more preferably from 0.7 to 0.8% by weight of molybdenum. Molybdenum can serve to prevent grain boundary embrittlement and contributes to resistance to tempering. Nevertheless, a high molybdenum content may have a detrimental effect on bainite transformation.

A molybdenum content within the above range may also result in lesser levels of macrosegregation in continuous, continuously cast billets and ingots from which the articles are made. In particular, it has been found that a Mo / Si weight ratio of preferably 3.5 to 33.3, more preferably 4 to 20, still more preferably 5 to 20, still more preferably 6 to 20, still more preferably 6 to 15 even more preferably from 6.5 to 15, more preferably from 6.6 to 14.5, even more preferably from 7 to 14, helps to ensure reduced segregation during the solidification of the steel.

The steel composition comprises 1.4 to 2.0% by weight of chromium. Apart from its positive effect on curability, it has been found that the chromium content has an importance for the type of carbides obtained during curing. If the concentration of chromium is too low, the relatively unwanted cementite phase is stabilized. The alloy therefore preferably comprises at least 1.5% by weight of chromium. On the other hand, the chromium content must be restricted to ensure, for example, sufficient solid solution carbon in the austenite phase during curing. To convert austenite into a sufficiently hard structure (57-63 HRC) at low temperatures during quenching, it must have enough dissolved carbon and optionally nitrogen. The steel alloy therefore comprises a maximum of 2.0% by weight chromium. The steel composition preferably comprises 1.5 to 1.8% by weight of chromium, more preferably 1.6 to 1.7% by weight of chromium.

The Cr / C weight ratio is preferably ≥ 2, as it has been found to help control the fluidity of the interdendritic steel fluid between the fully austenitic dendrites during cure.

The alloy preferably comprises molybdenum and chromium in a weight ratio of 0.35 ≦ Mo / Cr ≦ 0.71, more preferably in a weight ratio of 0.4 ≦ Mo / Cr ≦ 0.6. Such a ratio can increase the thermodynamic stability of the Cr-rich carbides.

The steel alloy composition comprises 0.7 to 0.9% by weight of manganese. Manganese serves to increase the stability of austenite relative to ferrite. Manganese can also be used to improve hardenability.

With a lower carbon content, the overall percentage of carbides recovered during curing is usually low, which has the advantage that there are usually fewer sites where microcracks are created. On the other hand, with fewer carbides remaining during austenization, the risk of austenite grain growth, which is poor for mechanical properties and wear, is higher.

The steel alloy comprises 0.03 to 0.15% by weight of vanadium. For example, 0.03 to 0.12 wt .-% vanadium, preferably 0.04 to 0.12 wt .-% vanadium, more preferably 0.05 to 0.1 wt .-% vanadium. The addition of vanadium to the steel allows the formation of vanadium-rich nano-sized precipitates (eg, carbides, nitrides, and / or carbonitrides) that form once the hot worked components have properly cooled to room temperature. The fine precipitates may be stuck to the previous austenite grain boundaries. Thus, the steel composition of the present invention may be resistant to over-austenization as compared to conventional bearing steels. In other words, the steel can be austenated at a relatively high temperature without excessive austenite grain growth. In addition, the slightly higher austenizing temperature, for example at 905 ° C, ensures better dissolution of the releasable elements (eg, chrome), which enhances hardenability. Such austenization temperature combined with steel chemistry means that a minimal content of cementite remains in the cured bearing component. As a result, the toughness of the bearing steel component can be improved, as well as its fatigue life and micro-defect tolerance.

In addition, and again, to prevent any excessive austenite grain growth during curing, it may be advantageous to add other microalloy additions, and optionally nitrogen, to form small, very fine precipitates pinning the previous austenite grain boundaries. For this purpose, the elements Ta and / or Nb may be added to form carbides, nitrides and / or carbonitrides.

In some embodiments, nitrogen is added so that the steel alloy has 50 to 350 ppm of nitrogen, preferably between 100 and 350 ppm of nitrogen. In other embodiments, there is no optional addition of nitrogen. Nevertheless, the alloy may necessarily have at least 50 ppm of nitrogen due to its exposure to the atmosphere.

Preferably, the added nitrogen steel alloy further comprises one or more of the following alloying elements in the following weight percentages: up to 0.1 weight percent niobium; and up to 0.2 wt% tantalum.

In the present work, it has been found that the formation of vanadium-rich and nitrogen-containing precipitates significantly improves both the strength and hardness of the final bearing steel structures, resulting in better resistance to rolling contact fatigue.

In examples of the steel alloy comprising vanadium and added nitrogen, the formation of vanadium-rich and nitrogen-containing precipitates is preferred over the formation of vanadium carbides, since the former are thermodynamically more stable. For a given level of vanadium carbides and vanadium nitrides, the vanadium nitrides tend to be smaller, more stable, and more effective at pinning the previous austenite grain boundaries. Vanadium-rich and nitrogen-containing precipitates also contribute more to reinforcing the bearing steel structure.

Preferably, the steel alloy comprises not more than 0.1% by weight of aluminum, more preferably not more than 0.05% by weight of aluminum. Aluminum is usually present in such small quantities due to the steel deoxidation process. More preferably, the steel alloy is free of aluminum, especially when the steel alloy has one or more of the micro-alloying elements (V and / or Nb and / or Ta). The presence of aluminum in this case is undesirable because nitrogen can be lost due to the formation of aluminum nitrides. Nevertheless, if the presence of a small amount of aluminum is unavoidable, the alloy may have aluminum and nitrogen in a weight percent ratio of 0.014 ≦ Al / N ≦ 0.6, preferably 0.014 ≦ Al / N ≦ 0.1. This ratio ensures that not all of the nitrogen is bound to the aluminum so that some nitrogen remains available to form, for example, vanadium-rich precipitates, thereby refining and stabilizing them.

As noted, the steel composition may optionally include one or more of the following elements:

0 to 0.25% by weight of nickel (for example 0.02 to 0.2% by weight of nickel)
0 to 0.3% by weight of copper (for example 0.02 to 0.2% by weight of copper)
0 to 0.2% by weight of cobalt (for example 0.05 to 0.2% by weight of cobalt)
0 to 0.1% by weight of aluminum (for example 0.05 to 0.1% by weight of aluminum)
0 to 0.1% by weight of niobium (for example 0.05 to 0.1% by weight of niobium)
0 to 0.2% by weight of tantalum (for example 0.05 to 0.2% by weight of tantalum)
0 to 0.035% by weight of nitrogen (for example 50 to 350 ppm of nitrogen)

It should be understood that the steel alloy described herein may have unavoidable impurities, although it is unlikely that these total exceed 0.03 wt .-% e of the composition. Preferably, the alloys include unavoidable impurities in an amount of not more than 0.1% by weight of the composition, more preferably not more than 0.05% by weight of the composition. In particular, the steel composition may also include one or more contaminating elements. An incomplete list of contaminants includes, for example:

0 to 0.025 wt .-% phosphorus
0 to 0.015% by weight of sulfur
0 to 0.04 wt% arsenic
0 to 0.075 wt .-% tin
0 to 0.075 wt .-% antimony
0 to 0.002% by weight of lead
0 to 0.003 wt% boron

The steel alloy composition preferably comprises little or no sulfur, for example 0 to 0.15% by weight sulfur.

The steel alloy composition preferably comprises little or no phosphorus, for example 0 to 0.025 weight percent phosphorus.

The steel composition preferably comprises ≤ 15 ppm oxygen. Oxygen may be present as an impurity. The steel composition preferably comprises ≤30 ppm of titanium. Titanium may be present as an impurity. The steel composition preferably comprises ≤ 10 ppm of boron. Boron may be present as an impurity of, for example, 1 to 5 ppm.

The steel composition preferably comprises ≤ 50 ppm calcium. Calcium may be present as an impurity, but it may also be intentionally added in very small amounts, for example 1 to 10 ppm.

The steel alloy composition may consist essentially of said elements. It is therefore to be understood that in addition to the elements which are mandatory, other unspecified elements may be present in the composition, provided that the essential properties of the composition are not materially affected by their presence.

Examples of bearing components according to the present invention include a rolling element (for example, ball, cylinder or tapered roller element), an inner ring, and an outer ring. The present invention may also provide a bearing with a bearing component as described herein.

• i) Kontinuierliches Stranggießen der hierin beschriebenen Stahllegierung, und
• ii) Ausbilden einer Lagerkomponente aus der kontinuierlich stranggegossenen Stahllegierung.

The steel alloy as described herein may be formed into a bearing component by continuously casting the alloy. The present invention further provides a method of making a bearing component, the method comprising:

• i) continuously casting the steel alloy described herein, and
• ii) forming a bearing component of the continuously cast steel alloy.

The alloy, as described herein, exhibits reduced macrosegregation and lends itself to continuous continuous casting processes. In particular, it has been found that a Mo / Si weight ratio of preferably 3.5 to 33.3, more preferably 4 to 20, more preferably 5 to 20, even more preferably 6 to 20, still more preferably 6 to 15, is useful to reduce segregation in continuously cast billets or ingots. Despite the desire not to be bound by theory, it is believed that the Mo / Si ratio within these limits helps to control the fluidity of the interdendritic steel fluid between the fully austenitic dendrites during cure. In addition, for the same reason, it is preferable to have a Cr / C weight% ratio of 2 or more.

In the manufacture of a bearing component, the steel alloy composition may be subjected to a heat treatment (austenization) such that the martensite start temperature is kept sufficiently low that the formation of a fully bainite or substantially fully bainitic structure (microstructure) is achieved. By a fully bainitic structure is meant that, after austenization and subsequent quenching, the steel articles are maintained at a temperature just above the martensite start temperature to begin transformation into bainite. The bainitic structure is fine and the resulting steel has a high hardness. Optionally, carbides / nitrides / carbonitrides may also be present.

It has also been found that the steel composition is suitable for martensitic heat treatment and tempering in which the steel articles, for example, bearing components, are usually quenched in oil after austenization to a temperature below the martensite start temperature. The components can then be cooled to room temperature, followed by a wash in cold water (about 5 ° C) before the final annealing step. The martensitic hardness has the advantage of reducing costs in terms of the process being faster than the bainitic one Forming processes. The material also has a harder structure. Optionally, carbides / nitrides / carbonitrides may also be present in the microstructure. It is also possible that the steel component has a mixed martensitic / bainitic structure, depending on the desired balance between hardness / residual stress profile. Again, optional carbides / nitrides / carbonitrides may also be present.

Optimization of the Mo / Si weight ratio, for example, from 3.5 to 3.3, preferably from 4 to 20, more preferably from 5 to 20, even more preferably from 6 to 20, more preferably from 6 to 15 has no negative influence on the Starting resistance of the steel. Consequently, it is possible to achieve a hardness of at least 60 HRC in the final bainitic transformed components, while at the same time providing a steel composition specially adapted for continuous casting. The starting resistance of the thus cured structure can also provide superior resistance to rolling contact fatigue.

The present invention will now be further described by way of example with reference to a suitable heat treatment of the steel alloy for the bearing component.

Austenization (hardening) of bearing components made of the present steel alloy is usually within a temperature range of 800 ° C to 900 ° C, preferably 840 to 900 ° C, more preferably 840 to 890 ° C for 10 to 70 minutes, preferably 10 to 60 minutes, executed. The austenite, refined chromium-rich carbides are present primarily at the end of the austenizing process shortly before the subsequent cooling. Optionally, as demonstrated in the previous section, vanadium-rich nitrogen-containing precipitates may also be present during curing. Such vanadium precipitates aid in refining the austenite grains, especially at higher austenitizing temperatures and / or at long hold times, which are commonly used when greater hardenability is required for making thick bearing component sections. The refined grains result in better toughness as well as greater strength and hardness of the final bearing steel product.

Immediately after the austenization, the bearing components are quenched using a suitable medium so that the entire reconstructive transformation products are avoided during cooling and martensite, bainite (bainite ferrite), or both structures are obtained in the steel microstructure, with only a small one Amount of retained austenite remains after tempering of the martensite-containing components or after the bainite transformation has ended. Thereafter, the bearing components are usually cooled to room temperature.

Subsequent deep freezing and / or tempering may be used to further reduce the residual austenite content, which ensures higher hardness and strength with its positive effect on rolling contact fatigue resistance. In addition, it has been found that a lower retained austenite content improves the dimensional stability of the bearing components, allowing them to be used in requesting bearing applications where the application temperature is higher than usual.

In view of the low carbon content, it has been found that the steel is particularly suitable for surface induction hardening and tempering. In this case, the microstructure usually comprises tempered martensite. Optionally, carbides / nitrites / carbonitrides may also be present.

The lower carbon content in the steel according to the present invention also means that it is easier to butt the steel compared to conventional higher carbon steels.

Examples

The invention will now be further described with reference to the following non-limiting examples.

Steel 1, comprising in% by weight:

• C: 0.75
• Si: 0.1
• Mn: 0.8
• Mo: 0.7
• Cr: 1.6
• Ni: 0.1
• Cu: 0.2
• V: 0.1
• P: max 0.01
• S: max 0.015
• As + Sn + Sb: max 0.075
• Pb: max 0.002
• Al: max 0.050
• Fe: rest

The oxygen content should be less than 10 ppm, the titanium content less than 30 ppm and the calcium content less than 10 ppm. Nitrogen is present as a trace element (at least 50 ppm). The maximum limit for As is 0.04 wt%.

Steel 2, comprising in% by weight:

• C: 0.75
• Si: 0.05
• Mn: 0.8
• Mo: 0.7
• Cr: 1.6
• Ni: 0.1
• Cu: 0.2
• V: 0.1
• P: max 0.01
• S: max 0.015
• As + Sn + Sb: max 0.075
• Pb: max 0.002
• Al: max 0.050
• Fe: rest

The oxygen content should be less than 10 ppm, the titanium content less than 30 ppm and the calcium content less than 10 ppm. Nitrogen is present as a trace element (at least 50 ppm). The maximum limit for As is 0.04 wt%.

Fully bainitic-cured components prepared from the above reference steel compositions 1 and 2 show a hardness of about 60 HRC or higher.

Comparative steel 1, comprising in wt .-%:

• C: 0.75
• Si: 0.2
• Mn: 0.8
• Mo: 0.36
• Cr: 1.6
• Ni: 0.1
• Cu: 0.2
• V: 0.1
• P: max 0.01
• S: max 0.015
• As + Sn + Sb: max 0.075
• Pb: max 0.002
• Al: max 0.050
• Fe: rest

The oxygen content should be less than 10 ppm, the titanium content less than 30 ppm and the calcium content less than 10 ppm. Nitrogen is present as a trace element (at least 50 ppm). The maximum limit for As is 0.04 wt%.

Comparative steel 2, comprising in% by weight:

• C: 0.75
• Si: 0.35
• Mn: 0.8
• Mo: 0.36
• Cr: 1.6
• Ni: 0.1
• Cu: 0.2
• V: 0.1
• P: max 0.01
• S: max 0.015
• As + Sn + Sb: max 0.075
• Pb: max 0.002
• Al: max 0.050
• Fe: rest

The oxygen content should be less than 10 ppm, the titanium content less than 30 ppm and the calcium content less than 10 ppm. Nitrogen is present as a trace element (at least 50 ppm). The maximum limit for As is 0.04 wt%.

Comparative steel 3, comprising in% by weight:

• C: 0.75
• Si: 0.05
• Mn: 0.8
• Mo: 0.5
• Cr: 1.6
• Ni: 0.1
• Cu: 0.2
• V: 0.1
• P: max 0.01
• S: max 0.015
• As + Sn + Sb: max 0.075
• Pb: max 0.002
• Al: max 0.050
• Fe: rest

The oxygen content should be less than 10 ppm, the titanium content less than 30 ppm and the calcium content less than 10 ppm. Nitrogen is present as a trace element (at least 50 ppm). The maximum limit for As is 0.04 wt%.

The effect on curing retention at 260 ° C temper for 1 hour was examined. For the reference steel compositions according to the above examples, the change in hardness (Vickers hardness ΔHv) was about +7.5 (steel 1), +4.5 (steel 2), 0 (comparative steel 1), +7 (comparative steel 2) and -3 (comparative steel 3). So the best results were obtained for Steels 1 and 2. Steels 1 and 2 are also suitable for continuous casting since they have reduced macrosegregation effects. While Comparative Steel 2 also shows a good result in terms of hardness, the high silicon content in this example (which is expected to improve the starting resistance) is not suitable even for continuous casting considering the relatively significant macrosgregation effect. The same applies to comparative steel 1, although to a lesser extent.

The following two other examples (V91 and V92) were also compared for macrosegregation.

Comparative steel V91, comprising in% by weight:

• C: 0.953
• Si: 0.308
• Mn: 0.671
• Mo: 0.245
• Cr: 1.721
• Ni: 0.175
• Cu: 0.155
• V: 0.01
• N: 0.0093
• Al: 0.007
• Nb: 0.002
• Sn: 0.012
• P: 0.017
• S: 0.009
• B: 0.0002
• As + Sn + Sb: max 0.075
• Fe: rest

The oxygen content should be less than 10 ppm, the titanium content less than 30 ppm and the calcium content less than 10 ppm. The maximum limit for As is 0.04 wt%.

Steel V92, comprising in% by weight:

• C: 0.749
• Si: 0.134
• Mn: 0.808
• Mo: 0.705
• Cr: 1,593
• Ni: 0.114
• Cu: 0.202
• V: 0.112
• N: 0.0049
• Al: 0.007
• Nb: 0.002
• Sn: 0.002
• P: 0.006
• S: 0.005
• B: 0.0003
• As + Sn + Sb: max 0.075
• Fe: rest

The oxygen content should be less than 10 ppm, the titanium content less than 30 ppm and the calcium content less than 10 ppm. The maximum limit for As is 0.04 wt%.

The two steel alloys V91 and V92 were melted in vacuum (vacuum induction melt) and then cast into sand molds. Their chemical composition is given above.

After molding, the beginning and end of each ingot were separated and discarded. Thereafter, the ingots were homogenized at 1200 ° C for a minimum of six hours and then cooled in the oven.

The ingots were cold charged and heated to their temperature at a rate of 100 ° C / hr. heated. Once the desired temperature was reached, the total hold time was 8 hours at that temperature to ensure that the mid-areas of each ingot were pervaded for at least six hours.

The furnace atmosphere was controlled using a continuous flow of nitrogen gas, initially at a rate of 28 l / min. While cooling to room temperature, the nitrogen gas flow rate was increased to 100 L / min. Nevertheless, the cooling rate of the ingots was sufficiently slow.

Two slices were separated from each ingot and were then grounded and finish polished prior to macroetching in accordance with the ASTM E 381 standard to expose the so-cured structure of each steel.

The macroetched sections of both steels were then compared. The steel alloy V92 showed a structure finer than that of the comparative reference steel alloy V91.

The bearing component of the present invention is formed of a steel alloy having a higher hardness, higher relative weldability, higher hardenability and toughness, and higher resistance to rolling contact fatigue, wear and creep as well as a higher tolerance to micro-defects. In addition, it also showed reduced segregation during continuous casting.

The foregoing detailed description has been provided by way of explanation and illustration and is not intended to limit the scope of the appended claims. Many variations in the presently preferred embodiments illustrated herein will be apparent to one of ordinary skill in the art and remain within the scope of the appended claims and their equivalents.

Claims (14)

A bearing component formed from a steel alloy comprising: 0.7 to 0.9% by weight of carbon, 0.05 to 0.16% by weight of silicon, 0.7 to 0.9% by weight of manganese, 1.4 up to 2.0% by weight of chromium, 0.7 to 1.0% by weight of molybdenum, 0.03 to 0.15% by weight of vanadium, 0 to 0.25% by weight of nickel, 0 to 0.3 wt .-% copper, 0 to 0.2 wt .-% cobalt, 0 to 0.1 wt .-% aluminum, 0 to 0.1 wt .-% niobium, 0 to 0.2 wt % Tantalum, 0 to 0.025 wt% phosphorus, 0 to 0.015 wt% sulfur, 0 to 0.075 wt% tin, 0 to 0.075 wt% antimony, 0 to 0.04 wt% Arsenic, 0 to 0.002 wt% lead, up to 350 ppm nitrogen, up to 20 ppm oxygen, up to 50 ppm calcium, up to 30 ppm boron, up to 50 ppm titanium, balance iron together with any unavoidable impurities. A bearing component according to claim 1, wherein the steel alloy comprises 0.7 to 0.8% by weight of carbon, preferably 0.72 to 0.78% by weight of carbon. A bearing component according to claim 1 or 2, wherein the steel alloy comprises 0.06 to 0.16% by weight of silicon, more preferably 0.8 to 0.14% by weight of silicon. Bearing component according to one of the preceding claims, wherein the steel alloy comprises 0.7 to 0.9 wt .-% molybdenum, preferably 0.7 to 0.8 wt .-% molybdenum. Bearing component according to one of the preceding claims, wherein the steel alloy molybdenum and silicon in a weight ratio of 3.5 ≤ Mo / Si ≤ 33.3, preferably 4 ≤ Mo / Si ≤ 20 has. Bearing component according to one of the preceding claims, wherein the steel alloy molybdenum and chromium in a weight ratio of 0.35 ≤ Mo / Cr ≤ 0.71, preferably 0.4 ≤ Mo / Cr ≤ 0.6. Bearing component according to one of the preceding claims, wherein the steel alloy has chromium and carbon in a weight ratio of Cr / C ratio ≥ 2. Bearing component according to one of the preceding claims, wherein the steel alloy comprises 0.03 to 0.12 wt .-% vanadium, preferably 0.05 to 0.1 wt .-% vanadium. Bearing component according to one of the preceding claims, wherein the steel alloy has 50 to 350 ppm of nitrogen. Bearing component according to one of the preceding claims, wherein the steel alloy has at least 100 ppm of nitrogen. Bearing component according to one of the preceding claims, wherein the steel alloy has a bainitic and / or martensitic microstructure, optionally with carbides, nitrites and / or carbonitrides. Bearing component according to one of the preceding claims, wherein the bearing component is a rolling element or an inner ring or an outer ring for a bearing. Bearing with a bearing component according to one of the preceding claims. A method of manufacturing a bearing component, the method comprising: i) Continuously casting a steel alloy composition with: 0.7 to 0.9% by weight of carbon, 0.05 to 0.16% by weight of silicon, 0.7 to 0.9 wt.% Manganese, 1.4 to 2.0% by weight of chromium, From 0.7 to 1.0% by weight of molybdenum, 0.03 to 0.15% by weight of vanadium, 0 to 0.25 wt% nickel, 0 to 0.3% by weight of copper, 0 to 0.2% by weight of cobalt, 0 to 0.1% by weight of aluminum, 0 to 0.1% by weight of niobium, 0 to 0.2 wt% tantalum, 0 to 0.025 wt.% Phosphorus, 0 to 0.015% by weight of sulfur, 0 to 0.075 wt% tin, 0 to 0.075 wt.% Antimony, 0 to 0.04 wt.% Arsenic, 0 to 0.002 wt.% Lead, up to 350 ppm nitrogen, up to 20 ppm oxygen, up to 50 ppm calcium, up to 30 ppm boron, up to 50 ppm titanium, as the remainder iron along with any unavoidable impurities. ii) forming a bearing component from the continuously formed steel alloy.